Recruiting

Vitamin D3 & K2

Sponsor:

Madigan Army Medical Center

Code:

NCT07199829

Conditions

Hypovitaminosis D

Hypovitaminosis

Eligibility Criteria

Sex: All

Age: 18 - 69

Healthy Volunteers: Accepted

Interventions

Vitamin Arm 1

Vitamin Arm 2

Vitamin Arm 3

Placebo

Study Details

Brief summary:

The main purpose of this research study is to learn about the effects of supplemental vitamin D3 and vitamin K2 on blood levels and the gut microbial community, called the gut microbiome. There are many influences on blood levels of vitamin D and K to include your dietary intake, lifestyle behaviors (physical activity, sleep), genetic alterations in metabolism of these vitamins, and the gut microbial abundance and diversity. You will be asked to take one capsule containing vitamin D3 (125 mcg), vitamin K2 (180 mcg), a combination of vitamins D3 and K2 (same doses as previous), or a placebo powder for 90 days. You will also be asked to complete questionnaires, undergo body composition and blood pressure measurements, provide blood samples and a stool swab, all on 2 occasions about 3 - 4 months apart. By conducting this study, we aim to identify the frequency of common genetic alterations in vitamins D and K metabolism and establish the impact on the gut microbiome for the first time. Your participation in this study will last about 4 - 6 months and include up to 3 visits.

Conditions

Hypovitaminosis D

Hypovitaminosis

Study ID

NCT07199829

Start date

Mar 27, 2025

Status verified date

Sep, 2025

Completion date

Mar, 2026

Anticipated

Primary completion date

Mar, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 69

Healthy Volunteers: Accepted

Inclusion Criteria:

  • able to read and understand English
  • 25 OHD serum level equal to or less than 30 ng/mL
  • willing to discontinue vitamin D3 and/or K2 supplements for 4.5 months
  • military beneficiary (Active Duty, Retired, Dependent)
  • remaining employed at workplace for 6 months

Exclusion Criteria:

  • Diagnosed medical condition that prevents nutrient absorption from food (e.g. Inflammatory Bowel Disease, Celiac Disease, post-Roux-en-Y/Gastric sleeve surgery)
  • Pregnant or breastfeeding
  • Current antibiotic use or within past 3 months
  • Current anticoagulant use or within past 3 months
  • Current weight loss or fat malabsorption medication use (e.g. Glucagon-Like Peptide 1 agonists, Orlistat)
  • Allergies or sensitivities to methylcellulose, vitamin D (D3, D2), or vitamin K (K2, Menaquinone-4, Menaquinone-7)

Study Design

Enrollment

96 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

active comparator: Vitamin Arm 1

Vitamin D3 125 mcg taken orally once daily for 90 days

active comparator: Vitamin Arm 2

Vitamin K2 180 mcg taken orally once daily for 90 days

active comparator: Vitamin Arm 3

Vitamin D3 125 mcg combined with vitamin K2 180 mcg taken orally once daily for 90 days

placebo comparator: Placebo Arm

Inert capsule taken orally once daily for 90 days

Interventions

Vitamin Arm 1

Subject receives dietary supplement for 90 days

Vitamin Arm 2

Subject receives dietary supplement for 90 days

Vitamin Arm 3

Subject receives dietary supplement for 90 days

Placebo

Subject receives placebo for 90 days

Primary outcome measure

  • Gut microbiome composition [ Time Frame: 90 days ]
  • Gut microbiome richness [ Time Frame: 90 days ]
  • Gut microbiome diversity [ Time Frame: 90 days ]

Central Contacts and Locations

Locations

Madigan Army Medical Center

Recruiting

Tacoma, Washington, United States, 98431

Contacts

More Information

Sponsor

Madigan Army Medical Center

Last update posted

Sep 30, 2025

Last verified

Sep, 2025

Keywords

  • Hypovitaminosis D
  • Hypovitaminosis K
  • Gut microbiome

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by Madigan Army Medical Center on 2025-09-30.